Blastomycosis is a disease that is caused by infection with the fungus Blastomyces dermatitidis. Humans and other animals (particularly dogs) are infected by inhaling aerosolized fungal spores from soil where the organism dwells. At body temperature, these spores convert to yeast forms. Acute primary pulmonary infection caused by the yeast can produce an influenza or pneumonia syndrome. Progressive forms of disease can cause serious damage.
The best available tests for this disease involve using antigens isolated from B. dermatitidis yeast in competitive binding RIA tests. See U.S. Pat. No. 5,093,118 (WI-1 protein); J. Green et al., 4 Curr. Microbiol. 293-96 (1980) ("A" antigen); and R. Cox et al., 10 Infect. Immun. 42-47 (1974) ("B-ASWS" antigen). The disclosures of these and all other articles and patents referred to herein are incorporated by reference as if fully set forth herein.
Existing supplies of B-ASWS antigen and A antigen are impure (see K. Young et al., 33 Infect Immun. 171-177 (1981); M. Lancaster et al., 13 Infect Immun. 758-762 (1976)), and they appear to be a mixture of cell wall components. It has not been possible to determine what portions of these two antigen are responsible for the antigenic response.
While WI-1 protein has now been isolated in reasonable purity, no one had previously been able to obtain DNA that would express this protein apart from B. dermatitidis. The amino acid sequence of WI-1 had not previously been determined and the cysteine rich nature of the protein rendered conventional protein sequencing techniques unsuitable. In this regard, WI-1 resists cleavage. It also adopts unusual configurations in stringent cleavage conditions. Thus, to date WI-1 has had to be obtained using relatively costly and time consuming isolations from natural yeast.
Thus, a need exists for a way to more quickly provide large amounts of an antigen to B. dermatitidis at low cost, and at consistant purity.